What Causes Slight Engine Shaking at Idle?
2 Answers
There are several reasons for engine shaking at idle: 1. Dirty air filter: The air filter is designed to protect the engine and reduce wear. Simply replacing the air filter can solve this issue. 2. Broken high-voltage wire: A broken high-voltage wire refers to a severed conductor core in the high-voltage line, which can affect ignition and cause engine shaking. 3. Low idle speed: The engine's idle speed is preset in the computer. When the RPM drops below a certain range, the car's computer will automatically adjust it. 4. Abnormal water temperature: The engine's operating temperature has a normal range. If the water temperature is too high, it can cause premature ignition timing, changes in the air-fuel mixture, thinning of engine oil viscosity, and reduced lubrication performance. 5. Clogged fuel injectors: The fuel injectors in fuel-injected cars are critical components for fuel delivery and have a long lifespan, often reaching hundreds of thousands of kilometers. However, deposits in gasoline can clog the injector nozzles, leading to inconsistent fuel delivery across injectors. This inconsistency causes uneven cylinder operation, resulting in engine shaking.
I've been driving this car for over a decade and experienced idle vibration several times, mostly due to ignition system issues like aging spark plugs or excessive carbon buildup causing misfires. Once during a cold start, the car shook slightly, and upon inspection, I found the spark plug gap was too large - replacing them solved the problem. If the high-voltage wires or ignition coils fail, it can also cause unstable engine RPM. Regular cleaning of the intake tract and fuel injectors is recommended, as carbon deposits can lead to uneven combustion of the air-fuel mixture and affect idle stability. Addressing these issues early can prevent increased fuel consumption or engine wear, saving on repair costs.
